This study is a descriptive and experimental analysis of wing flapping in 1-21 day chicks (Gallus domesticus). The development of wing-flapping will be examined using stroboscopic, cinematographic and electromyographic (EMG) procedures. Flapping will be evoked using a device consisting of a carriage to which a chick is attached which slides down a 1.7 meter rod. Developmental variables to be investigated are: a) latency to first flap; b) flap rate (flaps/sec); c) flap amplitude (wing degrees/flap; d) between-wing synchronization (phase). The experimental part of the study evaluates the impact of postnatal long-and short-term bilateral and unilateral wing immobilization and amputation on the development of flapping. These experiments will indicate the role played by post-hatching practice, sensory input and trophic influence of the peripheral wing on the development of the neural circuitry that produces flapping. The research will provide a rigorous quantitative account of wing flapping and its neural correlates (pectoral muscle EMG's) from the time of hatching when the unfeathered wings show only slow, low amplitude movements until 3-weeks, a time when the wings are well-feathered and perform vigorous, cyclic, adult-type flapping. Since successful wing flapping involves the pattern of motor outflow to both wings, the investigation also deals with the broader issue of the development of between-limb coordination.